The present invention relates to generally a channel selector for a television receiver and more particularly a channel selector having an electronic tuner of the type in which the voltage applied across a voltage-variable reactance element is switched electronically in order to select the desired channel.
In the conventional channel selectors for television receivers, the tuning capacitors and coils are switched by a rotary switch in order to select the desired channel so that the conventional channel selectors are complex in construction, large in size and expensive to manufacture. Moreover, reliable and dependable channel selection cannot be attained when the contacts are worn out. In order to overcome these undesirable features, there has been devised and demonstrated the so-called electronic channel selector of the type in which a keyboard and a decimal-to-binary converter are used to select one of a plurality of variable resistors so that the voltage applied across a voltage-variable reactance element used as a tuning element may be changed depending upon the desired channel.
However, the variable resistors used in conventional electronic channel selectors are adversely affected by environmental conditions. In ambient condition of high temperatures and humidity variations in resistance and faulty switch contacts tend to occur so that the correct channel selection cannot be attained.